| 摘要 |
PURPOSE:To roll easily threads to a steel pipe at a high speed without crushing the pipe by using the steel pipe having a specified outside diameter and wall thickness as a work piece and rolling the pipe by means of two dies facing each other under specific conditions thereby forming the threads. CONSTITUTION:The steel pipe having 20-40mm., more preferably 25-35mm. outside diameter and the wall thickness of 10-15%, more preferably 10-12.5% of the outside diameter is used as the work piece. The conditions for rolling the threads to such steel pipe are as follows: The dies having 170-300mm. diameter and 70-100mm., more preferably about 80mm. width are used, the number of revolution of the dies is kept at 70-100rpm, more preferably at about 90rpm max. number of revolution and the rolling load is kept at 20-70tons, more preferably about 60tons max. load. The feed speed of the steel pipe is made 600-2,100mm./ min, more preferably 650-2,060mm./min and the steel pipe is rolled by means of the two dies facing each other in such a manner that the height of the thread ridge is made <=3.5mm., more preferably <=3mm.. |
